Cutting tools, cutting inserts, and insert holders in which they are retained for parting and grooving operations as disclosed in U.S. Pat. No. 4,801,224, are typically small in width and subjected to single direction cutting forces. These cutting forces, produced as a result of axial direction machine feed, are transmitted through the insert tip and the forward section of the insert holder lower surface.
Support of the insert is provided by a lower V-shaped insert holder male surface (when viewed in cross-section) extending parallel to the axial machine feed direction with an obtuse internal angle between the two surface components, corresponding with an equivalent V-shaped surface on the insert with an obtuse external angle between the two surface components, where large forces can be absorbed whilst minimizing the risk of fracturing the insert. The upper surfaces of both the insert and insert holder also share these same features.
U.S. Pat. No. 6,086,291 discloses a cutting tool for parting, grooving, and turning operations where each clamping surface includes a second V-shaped feature. A ridge style feature of narrower wedge angle is introduced along the length of the male V-shaped surface of the insert holder, and a flute style feature of narrower wedge angle is introduced along the length of the female V-shaped surface of the insert.
The insert and insert holder are manufactured such that when assembled, a small gap exists between the ridge and flute side surfaces. Thus, during operation, the wider obtuse angled V-shaped surfaces generally support the central main forces, and the narrower angled ridge and flute V-shaped surfaces generally support the transverse forces. The presence of a small gap between the ridge and flute side surfaces may give rise to an initial transverse movement of the insert of magnitude equal to the gap size at commencement of a turning operation.
U.S. Pat. No. 6,244,790 discloses a cutting tool for parting, grooving, and turning operations, introducing lower support surfaces with a series of intermeshing ridges and grooves of V-shaped profile, each with a common narrow wedge angle. This solution is aimed at providing increased stability of the insert within the insert holder against twisting, whilst, in theory, also reducing the risk of the insert lower surface splitting by providing a larger surface area for the clamping force to be distributed.
Distribution of the clamping force over a large surface area requires successful mating of, and simultaneous contact between, the several ridge surfaces extending the entire longitudinal direction of the cutting insert, and the equal number of grooves extending along the entire longitudinal direction of the cutting insert pocket.